add or subtract polynomials by simply combining like terms

(k^2-4k+7)+k^2+9k-3)

(w^3-2w^2-5)+(3w^2-11)

(9x-5y)+(3x+2y-7)

1 answer

To combine like terms in the given polynomials, we simply add or subtract the coefficients of the terms with the same degree. Here's how it's done for each expression:

1. \((k^2 - 4k + 7) + (k^2 + 9k - 3)\)

Combine like terms:

  • \(k^2\) terms: \(k^2 + k^2 = 2k^2\)
  • \(k\) terms: \(-4k + 9k = 5k\)
  • Constant terms: \(7 - 3 = 4\)

Result: \[ 2k^2 + 5k + 4 \]


2. \((w^3 - 2w^2 - 5) + (3w^2 - 11)\)

Combine like terms:

  • \(w^3\) terms: \(w^3\) (only one \(w^3\) term)
  • \(w^2\) terms: \(-2w^2 + 3w^2 = 1w^2\) or just \(w^2\)
  • Constant terms: \(-5 - 11 = -16\)

Result: \[ w^3 + w^2 - 16 \]


3. \((9x - 5y) + (3x + 2y - 7)\)

Combine like terms:

  • \(x\) terms: \(9x + 3x = 12x\)
  • \(y\) terms: \(-5y + 2y = -3y\)
  • Constant term: \(-7\) (only one constant term)

Result: \[ 12x - 3y - 7 \]


Final Results:

  1. \( 2k^2 + 5k + 4 \)
  2. \( w^3 + w^2 - 16 \)
  3. \( 12x - 3y - 7 \)